1. Field of the Invention
The invention relates to exercise equipment, more particularly to an adjustable dumbbell.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional adjustable dumbbell 10, as disclosed in U.S. Pat. No. 6,656,093 (see also U.S. Patent Application Publication No. 2004/0005969), includes a base 11 for supporting a plurality of weights 12, a hollow handle 13, two latches 14, and two adjustable units 15.
Each of the weights 12 includes a lateral channel 121, and a vertical groove 122 communicating with the lateral channel 121. The lateral channel 121 has a width greater than that of the vertical groove 122.
The hollow handle 13 has two blocks 132 provided respectively on two opposite ends thereof for engaging the vertical grooves 122 of the weights 12, and two conduits 133 laterally and respectively formed in the middle portions of the blocks 132. Each of the blocks 132 includes a passage 135 communicating with the respective conduit 133, and a plurality of spaced-apart apertures 134 communicating with the passage 135. Each of the apertures 134 has a diameter greater than the width of the passage 135.
Each of the latches 14 is inserted slidably into one of the blocks 132 via the corresponding conduit 133, and has a screw hole 141.
Each of the adjustable units 15 is provided at each end of the hollow handle 13, and includes a barrel 151 having a catch 152 provided in a bottom portion thereof for insertion into one of the apertures 134 in the corresponding block 132, a spring 153 disposed in the barrel 151 for biasing the catch 152 to engage one of the apertures 134 and for selectively or adjustably securing the latches 14 to the respective blocks 132, and a bolt 154 passing through the barrel 151 to engage threadedly the screw hole 141 in the corresponding latch 14. The bolt 154 is limited to slide and move along the passage 135 of the corresponding block 132 so that each latch 14 may also be limited to move and slide relative to the respective block 132.
In operation, when the catch 152 of the barrel 151 of each adjustable unit 15 is disengaged from the corresponding aperture 134 by pulling the barrel 151. away from the corresponding block 132 against the spring 153, each latch 14 may be moved and adjusted relative to the corresponding block 132. When each latch 14 is moved to engage the lateral channels 121 of all of the weights 12 on one end of the hollow handle 13, these weights 20 are secured to the corresponding block 132. The number of the weights 12 at each end of the hollow handle 13 can be adjusted by simply moving the latches 14 relative to the blocks 132, respectively.
In the aforementioned conventional adjustable dumbbell 10, the two adjustable units 15 are operated separately, and the catches 152 of the barrels 151 have to accurately spring back into the corresponding apertures 134 in the blocks 132 when the barrels 151 are released by the user.
Referring to FIGS. 3 and 4, another conventional adjustable dumbbell 20 includes a plurality of weights 22 provided on each end of a hollow handle 21, and two adjustable units 23. The user operates the two adjustable units 23 to balance the number of the weights 22 at each end of the hollow handle 21.